Polyesters, which are polymers containing an ester group (—C(═O)—O—C—) as part of their repeating chemical structure, are used in a wide variety of applications. Polyester fibers may be used in textiles and as reinforcing fibers in rubbers or in rigid composite materials. Polyester films or coatings may be flexible or rigid, with representative applications including but not limited to food or beverage containers, metallized films and photographic films and tapes. Representative applications of rigid polyester plastics including but are not limited to housings for electronic devices and automotive parts.
As with polymers in general, the physical properties of a polyester are determined by the chemical structure of the polyester, the nature of any other ingredients added to the polyester, and the processing techniques used to form a material from the polyester. For example, the chemical structure of a polyester may include aromatic and/or aliphatic organic groups. Alteration of the chemical structure, size and/or frequency of these groups in a polyester can allow for modification of the properties of the polymer.
It is desirable to expand the chemical structures present in polyesters, so as to expand the useful properties that can be provided by the polymers. For example, properties such as flexibility, toughness, etc. can be improved by incorporating chemical groups that lower the modulus or that can absorb energy, respectively. This expansion of chemical structures may be accomplished through post-polymerization processing, such as reaction with other reagents or blending with other polymers. It is especially desirable, however, to expand the chemical structures by introducing new chemical structures in the monomeric building blocks from which the polymer is formed.
It would be desirable to provide polyesters that include chemical groups not previously observed in a polyester. Preferably such modified polyesters can be formed using conventional synthetic techniques and equipment, without requiring post-polymerization treatment. Preferably the modified polyesters can be formed using monomeric building blocks that are readily available and inexpensive.